2 files changed, 22 insertions, 4 deletions

diff --git a/arch/x86/kernel/aperture_64.c b/arch/x86/kernel/aperture_64.c
index 8c325b7f2d9b..c63f8d9fad3e 100644
--- a/arch/x86/kernel/aperture_64.c
+++ b/arch/x86/kernel/aperture_64.c
@@ -55,8 +55,9 @@ static u32 __init allocate_aperture(void)
         u32 aper_size;
         void *p;
 
-        if (fallback_aper_order > 7)
-                fallback_aper_order = 7;
+        /* aper_size should <= 1G */
+        if (fallback_aper_order > 5)
+                fallback_aper_order = 5;
         aper_size = (32 * 1024 * 1024) << fallback_aper_order;
 
         /*
@@ -65,7 +66,20 @@ static u32 __init allocate_aperture(void)
          * memory. Unfortunately we cannot move it up because that would
          * make the IOMMU useless.
          */
-        p = __alloc_bootmem_nopanic(aper_size, aper_size, 0);
+        /*
+         * using 512M as goal, in case kexec will load kernel_big
+         * that will do the on position decompress, and  could overlap with
+         * that positon with gart that is used.
+         * sequende:
+         * kernel_small
+         * ==> kexec (with kdump trigger path or previous doesn't shutdown gart)
+         * ==> kernel_small(gart area become e820_reserved)
+         * ==> kexec (with kdump trigger path or previous doesn't shutdown gart)
+         * ==> kerne_big (uncompressed size will be big than 64M or 128M)
+         * so don't use 512M below as gart iommu, leave the space for kernel
+         * code for safe
+         */
+        p = __alloc_bootmem_nopanic(aper_size, aper_size, 512ULL<<20);
         if (!p || __pa(p)+aper_size > 0xffffffff) {
                 printk(KERN_ERR
                         "Cannot allocate aperture memory hole (%p,%uK)\n",
diff --git a/arch/x86/kernel/pci-dma.c b/arch/x86/kernel/pci-dma.c
index 0c37f16b6950..1a017f00e867 100644
--- a/arch/x86/kernel/pci-dma.c
+++ b/arch/x86/kernel/pci-dma.c
@@ -77,10 +77,14 @@ void __init dma32_reserve_bootmem(void)
         if (end_pfn <= MAX_DMA32_PFN)
                 return;
 
+        /*
+         * check aperture_64.c allocate_aperture() for reason about
+         * using 512M as goal
+         */
         align = 64ULL<<20;
         size = round_up(dma32_bootmem_size, align);
         dma32_bootmem_ptr = __alloc_bootmem_nopanic(size, align,
-                                 __pa(MAX_DMA_ADDRESS));
+                                 512ULL<<20);
         if (dma32_bootmem_ptr)
                 dma32_bootmem_size = size;
         else